A Nucleus ${ } _ { M } ^ { N } X$

Short Answer

A nucleus ${ } _ { M } ^ { N } X$ undergoes one alpha decay followed by 3 beta-minus decays.
(a) What is the resulting nucleus in terms of $\mathrm { M }$ and $\mathrm { N }$ ?
(b) If there had been 3 beta-plus decays instead of the beta-minus decays, what would have been the resulting nucleus in terms of $M$ and $N$ ?